Dynamoelectric machine slot wedge and filler locking means

ABSTRACT

For retention of a coil in dynamoelectric machine core slots, a slot wedge is provided with a compressible end that is normally oversized in relation to the slot width. The wedge is compressed when driven through the slot. The oversized portion then expands when it reaches the first vent duct and locks the wedge in the slot. Another feature is to use a flexible insulating tape between the coil and the slot filler strips with ends extending from the slot so that they can be wrapped around the ends of the filler strips and be secured by a locking type wedge, which may be as described above, at each end of the stack.

United States Patent [191 Amasino et a1.

[ DYNAMOELECTRIC MACHINE SLOT WEDGE AND FILLER LOCKING MEANS [75] inventors; Richard L. Amasino, Trafford; Paul S. Johrde, Murrysville, both of Pa.

[73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

22 Filed: Apr. 26, 1971 21 Appl No.: 137,466

[52] US. Cl. 310/214 FOREIGN PATENTS OR APPLICATIONS 4/1958 Belgium. 310/214 11] 3,740,601 [451 June 19,1973

Primary Examiner-D. F. Duggan Attorney-A. T. Stratton, F. P. Lyle and Gordon H.

Te lfer [57] ABSTRACT For retention of a coil in dynamoelectric machine core slots, a slot wedge is provided with a compressible end that is normally oversized in relation to the slot width. The wedge is compressed when driven through the slot. The oversized portion then expands when it reaches the first vent duct and locks the wedge in the slot. Another feature is to use a flexible insulating tape between the coil and the slot filler strips with ends extending from the slot so that they can be wrapped around the ends of the tiller strips and be secured by a locking type wedge, which may be as described above, at each end of the stack.

I 5 Claims, 2 Drawing Figures Patented June 19, 1973 3,740,601 I FIGI.

WITNESSES INVENTORS Richard L Amoslno and Paul S. Johrde BY Z 1 4 f lfl r DYNAMOELECTRIC MACHINE SLOT WEDGE AND FILLER LOCKING MEANS BACKGROUND OF THE INVENTION elements a side filler driven between the coil and the adjacent slot wall, slot fillers above the coil at the slot opening and, over the slot fillers, a slot wedge. The slot wedge is configured to be driven in notches at the opening of the slot to prevent any radial movement of the wedge. Variously configured wedges have been used or disclosed in the past. Among them are slotted wedges that provide resiliency to permit the wedge to be driven in while giving a degree of extra secureness against the surfaces of the groove in which the wedge is positioned. US. Pat. Nos. 2,569,278 and 2,723,358 are representative of prior art showing slotted or grooved slot wedges.

To obtain positive locking of slot wedges as have been used in the past it has been necessary to provide an additional element outside the slot, adjacent to the end of the wedge, that is tied in or adhesively bonded to the core face. While generally effective, such additional elements for wedge locking are time consuming and expensive.

The slot fillers located between the slot wedge and the coil are also subject to dislocation in use if the wedge is not well secured. It is also possible that some longitudinal movement of a slot filler can occur even with a wedge securely in place.

SUMMARY OF THE INVENTION This invention provides a means for positive locking of slot wedges and slot fillers. A slot wedge, which is of relatively rigid insulating material, is made to be resilient and compressible at one end as by providing at that end one or more longitudinal grooves extending a short distance, such as one or two inches, from the end. Also at that end are laterally extending projections to give the slot wedge a normal dimension, when uncompressed, that is oversized in relation to the core slot dimension. Upon compression of this end of the slot wedge, the wedge can be inserted in the slot and driven through the first pack of laminations. When the compressed end of the slot wedge emerges from the first pack, it expands to normal size with the projections locking into the first vent duct in the core. Wedge movement in both longitudinal directions is avoided by employing such a locking wedge at each end of a stack which comprises a plurality of packs of iron so that the locking wedge head is disposed against the end surface of an adjacent wedge in an interior pack of the stack.

An additional feature is the use of a flexible strip of material, such as a glassfiber banding tape, disposed over the outside coil surface with ends extending from the slot. The slot fillers, which may be as previously constructed and used, are disposed over the flexible strip and slot wedges are positioned over the interior portions of the tiller strips. Before locking wedges are disposed at the ends of the slots, the flexible strip is wrapped around the filler strips and brought to the top surface of the filler strips. A locking wedge is driven in over this surface with an end of the flexible strip extending between the locking wedge and the adjacent wedge. This arrangement at each end of the coil slot permanently secures the elements in position. The locking wedge may take various forms among which is that described above having a compressible end and locking tabs.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partial view of the interior of a dynamoelectric machine stator embodying the present invention; and

FIG. 2 is a cross-sectional view taken along the line 11-11 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, the invention is shown embodied in a dynamoelectric machine having a stator core 10 that normally comprises a plurality of packs 12 of metallic laminations with ventilating ducts 31 between adjacent packs 12. Coil, slots 14, of which only one is shown, extend longitudinally through the core 10 for the disposition of coils 16, of which only one is shown, therein. The core 10 normally has the general configuration of a hollow cylinder of which only a small part is shown in FIG. 1. The invention is particularly described and applicable to the construction of stators of relatively large machines such as turbine generators, and has found particular application in vertically disposed water wheel generators. Vertical machines tend to present more frequent problems in retaining elements in the slots than do horizontal machines. However, the invention is not so limited and may be applied to stators of either horizontal or vertical disposition and may also be applied to rotor windings.

The coils 16 each comprise a plurality of conductors with an insulating covering around the conductors. Elements called side fillers (not shown) are normally disposed on one or both sides of the coils 16 to secure the coils from lateral movement in the slot 14. Securing of the coils 16 in the radial direction is effected by one or more slot fillers 18 disposed over the coil and by slot wedges 20, 21, 22 and 23 (of which four are shown in this example) that are positioned in notches or grooves 24 in the walls of slot 14 that fix their radial location.

In accordance with a preferred form of this invention there is first applied to the insulated surface of coil 16 a layer 26 of flexible insulating material, such as a strip of glass fiber banding tape, of a length which is greater than the slot length. Over the flexible strip 26 are disposed one or more relatively more rigid slot filler members 18. Then are positioned interior wedges 21 and 22 in the slot 14 by driving them into notches 24. Interior wedges 21 and 22 may be as previously formed, merely requiring a configuration that fits within the slot with substantial tightness but loose enough to be driven. Thus wedges 21 and 22 may have uniform lateral dimensions. After location of a sufficient number of interior wedges 21 and 22, the flexible strip 26 is wrapped around the ends of the filler strips 18 and past the outer ends 27 of the interior wedges 21 and 22. Locking wedges 20 and 23 are then applied one at each end of the stack 10, by being driven into the slot 14 over the tape 26.

FIG. 1 shows a preferred form of locking wedges 20 and 23 (which may be identical) in accordance with this invention. The interior end 28 of each wedge 20 and 23 is made to be resilient and compressible, such as by one or more grooves 29 extending longitudinally from that end. The ends 28 also have lateral projections 30 so that in the uncompressed state the ends 28 are oversized in relation to the lateral dimensions of the notches 24. There is sufficient resiliency provided by the grooves 29, however, that the ends 28 of the wedges 20 and 23 can be compressed and fit into the slot and driven through. Upon being driven through the end pack of core laminations the end 28 expands and locks by having the grooved edge against the end of adjacent wedge 21 or 22 and the projections 30 held against the face of the end core pack in vent duct 31. When such locking wedges are employed at both ends of the core 10 there is a permanent securing of the wedge, filler, and coil combination with the core.

The materials employed for the various elements may be as have been used in the past. The wedges 20, 21, 22 and 23 conveniently are of a resin impregnated glass fiber material. The grooves 29 which provide the resiliency may be saw cut into the ends 28. Typical thicknesses for the wedges are in the range of about 0.15 inch to about 0.20 inch. The width of the grooves 29 is at least sufficient to permit enough flexing of the extended portions 30 so the end 28 can be driven through the grooves 24. As an example, locking wedges as shown have been made with three grooves 29, each having a width of about 0.06 inch where the maximum width of the wedge at end 28 is about 1.10 inch and a portion of the wedge that remains in the channel 24, and fits relatively secure in that channel is about 0.95 inch. The outer two grooves 29 were about 1.5 inch long while the center groove 29 was about 1 inch long.

The arrangement in accordance with this invention may be practiced without employing any adhesive material between the various elements. There may, however, bean application of an adhesive material to the extended end of the flexible insulating strip 26 (and/or to surfaces of the slot fillers and locking wedges) so that when the locking wedge 20 or 23 is driven in, the flexible strip 26 is bonded by the adhesive to both the end of the filler strips 18 and to the locking wedge 20 or 23.

As an additional alternative, when wedges 20 and 23 are in place, the grooves 29 may be filled with a material, such as an air-hardenable viscous resin, which when hard will prevent deflection of elements 30 that could result in movement of the wedges.

While the illustrative embodiment concerns a core 10 with a plurality of spaced packs 12, it can be seen that substantial advantage can also be obtained in applying the present invention to cores with a single, continuous pack of laminations. For example, the locking wedge 20 may be used as the only slot wedge in a continuous core with positive insurance of movement in one direction. Additional means, such as have been previously used, may be used to prevent movement in the other longitudinal direction, if necessary or desired.

I claim as my invention:

1. A dynamoelectric machine comprising:

a core comprising a plurality of stacked packs of laminations, including first and second end packs and at least one interior pack, with a ventilation duct between adjacent ones of said packs;

a slot in said core extending through said plurality of core packs;

a coil disposed in said slot;

means for retaining said coil in said slot including a plurality of slot wedges of insulating material disposed in laterally positioned grooves near the opening of said slot over said coil, said plurality of slot wedges including first and second locking slot wedges in said first and second end packs, respectively, and at least one interior slot wedge in said at least one interior pack, one end of each of said locking slot wedges being resiliently compressible and having lateral projections that lock said wedge in position by being secured between an end of an interior slot wedge and a face of one of said end packs, said at least one interior slot wedge having substantially uniform lateral dimensions.

2. The subject matter of claim 1 wherein: said resiliently compressible end of each of said locking slot wedges is provided with at least one longitudinally extending groove.

3. A dynamoelectric machine comprising: a core including a plurality of spaced packs of metallic lamina tions; a slot in said core; a coil in said slot; means for securing said coil in said slot including at least one slot filler of insulating material disposed over said coil and at least one slot wedge member of insulating material disposed over said filler and engaged within grooves in the lateral surfaces of said slot, and a layer of flexible insulating material disposed between said slot filler and said coil and wrapped longitudinally around each end of said slot filler and under an end slot wedge that is securely locked in position to prevent longitudinal movement.

4. The subject matter of claim 3 wherein said end slot wedge comprises a flat member of relatively rigid insulating material with one end being resiliently compressible and with lateral projections so that when in position in said grooves in an end one of said packs of said core the lateral projections expand within the space between adjacent packs.

5. The subject matter of claim 4 wherein the compressibly resilient end of said end slot wedge is provided with longitudinal grooves from said end with said lateral projections. 

1. A dynamoelectric machine comprising: a core comprising a plurality of stacked packs of laminations, including first and second end packs and at least one interior pack, with a ventilation duct between adjacent ones of said packs; a slot in said core extending through said plurality of core packs; a coil disposed in said slot; means for retaining said coil in said slot including a plurality of slot wedges of insulating material disposed in laterally positioned grooves near the opening of said slot over said coil, said plurality of slot wedges including first and second locking slot wedges in said first and second end packs, respectively, and at least one interior slot wedge in said at least one interior pack, one end of each of said locking slot wedges being resiliently compressible and having lateral projections that lock said wedge in position by being secured between an end of an interior slot wedge and a face of one of said end packs, said at least one interior slot wedge having substantially uniform lateral dimensions.
 2. The subject matter of claim 1 wherein: said resiliently compressible end of each of said locking slot wedges is provided with at least one longitudinally extending groove.
 3. A dynamoelectric machine comprising: a core including a plurality of spaced packs of metallic laminations; a slot in said core; a coil in said slot; means for securing said coil in said slot including at least one slot filler of insulating material disposed over said coil and at least one slot wedge member of insulating material disposed over said filler and engaged within grooves in the lateral surfaces of said slot, and a layer of flexible insulating material disposed between said slot filler and said coil and wrapped longitudinally around each end of said slot filler and under an end slot wedge that is securely locked in position to prevent longitudinal movement.
 4. The subject matter of claim 3 wherein said end slot wedge comprises a flat member of relatively rigid insulating material with one end being resiliently compressible and with lateral projections so that when in position in said grooves in an end one of said packs of said core the lateral projections expand within the space between adjacent packs.
 5. The subject matter of claim 4 wherein the compressibly resilient end of said end slot wedge is provided with longitudinal grooves from said end with said lateral projections. 